Silicon-on-Insulator (SOI) optical devices may include an active surface layer that includes waveguides, optical modulators, detectors, CMOS circuitry, metal leads for interfacing with external semiconductor chips, and the like. The active surface can also include photodetectors that convert the light propagating in the waveguides into electrical signals. Although crystalline silicon is excellent at forming waveguides with submicron dimensions, silicon is a poor material for both generating and absorbing light at wavelengths used for digital communication. While III-V semiconductors are better suitable for photodetectors, these material are expensive and their fabrication techniques are less advances than those used for silicon.
To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures. It is contemplated that elements disclosed in one embodiment may be beneficially utilized on other embodiments without specific recitation.